G Leitz at Boehringer Ingelheim and Donna Mildvan at Beth Isreal Hospital reported on this study whose aim was to determine the effects of nevirapine treatment on the pharmacokinetics of EE/NET.

This was an open label study in HIV-1 infected women who have been on a stable antiretroviral therapy for at least 30 days prior to study entry with a CD4+ T-cell count of >100 cell/mm3 and a viral load of <400 copies/mL. Oral administration of single dose of EE/NET tablet, followed by thirty-four hours of pharmacokinetic sampling (Days 0-1). Oral administration of 200 mg NVP QD for two weeks followed by 200 mg NVP bid for an additional two weeks (Study Days 2 - 29). On Study Day 30, a single 200 mg dose of NVP and a single dose of EE/NET were administered in the morning followed by thirty-four hours of pharmacokinetic sampling.

Preliminary results: NVP coadministration with a single dose of EE/NET resulted in a median reduction in the AUC of approximately 19% (95% CI, range 0.61-1.08, p < 0.05). Although there was no significant effect on EE Cmax, the median change in the half-life of EE decreased (15.7 h versus 11.6 h) after NVP administration (p < 0.05). Likewise, NVP coadministration resulted in a reduction in the median NET AUC of approximately 18%, (95% CI, range 0.67-0.96, p < 0.05). NVP average steady-state peak (7.8 + 1.9 mcg/ml) concentrations and apparent oral clearance (2.88 + 1.09 L/h) were not influenced by EE/NET and were within the range of values that have been observed with historical controls.

The authors concluded that NVP administration resulted in a modest increase in clearance of EE and NET. The effect of NVP on EE/NET is consistent with P450 induction of CYP3A4. The PK data suggests that oral contraceptives should not be used as the primary means of contraception when NVP is prescribed to women of childbearing potential.